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Article contents:[[tags: eggs]] [[toc:]] == byte-sequence === Description {{byte-sequence}} aims to provide a SRFI-1-inspired API for manipulating byte sequences encoded as bytevectors. In borrows inspiration from the Haskell [[https://hackage.haskell.org/package/bytestring/|bytestring]] library. {{byte-sequence}} is the successor of the {{byte-blob}} egg. All procedures have been renamed from {{byte-blob-*}} to {{byte-sequence-*}}, and the conversion procedures {{blob->byte-blob}} and {{byte-blob->blob}} are now {{bytevector->byte-sequence}} and {{byte-sequence->bytevector}}. === Library Procedures ==== Predicates <procedure>(byte-sequence? X) => BOOL</procedure> Returns {{#t}} if the given object is a byte-sequence, {{#f}} otherwise. <procedure>(byte-sequence-empty? BYTE-SEQUENCE) => BOOL</procedure> Returns {{#t}} if the given byte-sequence is empty, {{#f}} otherwise. <procedure>(byte-sequence-valid-utf8? BYTE-SEQUENCE) => BOOL</procedure> Returns {{#t}} if the bytes of the given byte-sequence form a valid UTF-8 sequence, {{#f}} otherwise. The validation rejects malformed lead bytes, truncated sequences, UTF-16 surrogate code points (U+D800..U+DFFF), and encodings of values above U+10FFFF. <procedure>(byte-sequence-is-prefix-of? PREFIX BYTE-SEQUENCE) => BOOL</procedure> Returns {{#t}} if {{PREFIX}} is a prefix of {{BYTE-SEQUENCE}}, {{#f}} otherwise. <procedure>(byte-sequence-is-suffix-of? SUFFIX BYTE-SEQUENCE) => BOOL</procedure> Returns {{#t}} if {{SUFFIX}} is a suffix of {{BYTE-SEQUENCE}}, {{#f}} otherwise. ==== Constructors <procedure>(byte-sequence-empty) => BYTE-SEQUENCE</procedure> Returns an empty byte-sequence. <procedure>(byte-sequence-replicate N V) => BYTE-SEQUENCE</procedure> Returns a byte-sequence of length {{N}}, where each element is {{V}}. <procedure>(byte-sequence-cons X BYTE-SEQUENCE) => BYTE-SEQUENCE</procedure> Analogous to list cons, but of complexity O(N), as it requires copying the elements of the byte-sequence argument. <procedure>(byte-sequence-snoc BYTE-SEQUENCE X) => BYTE-SEQUENCE</procedure> Analogous to {{byte-sequence-cons}}, but appends {{X}} at the end of the given byte-sequence. Of complexity O(N), as it requires copying the elements of the byte-sequence argument. <procedure>(byte-sequence-singleton X) => BYTE-SEQUENCE</procedure> Returns a byte-sequence of length 1 containing the byte {{X}}. <procedure>(bytevector->byte-sequence BYTEVECTOR) => BYTE-SEQUENCE</procedure> Returns a byte-sequence containing the elements of the given bytevector. <procedure>(list->byte-sequence LIST) => BYTE-SEQUENCE</procedure> Returns a byte-sequence containing the elements of {{LIST}}. <procedure>(string->byte-sequence STRING) => BYTE-SEQUENCE</procedure> Returns a byte-sequence containing the elements of {{STRING}}. ==== Accessors <procedure>(byte-sequence-length BYTE-SEQUENCE) => INTEGER</procedure> Returns the number of elements contained in the given byte-sequence. <procedure>(byte-sequence-car BYTE-SEQUENCE) => X</procedure> Returns the first element of a byte-sequence. The argument byte-sequence must be non-empty, or an exception will be thrown. <procedure>(byte-sequence-cdr BYTE-SEQUENCE) => BYTE-SEQUENCE</procedure> Returns a byte-sequence that contains the elements after the first element of the given byte-sequence. The argument byte-sequence must be non-empty, or an exception will be thrown. <procedure>(byte-sequence-last BYTE-SEQUENCE) => X</procedure> Returns the last element of a byte-sequence. The argument byte-sequence must be non-empty, or an exception will be thrown. <procedure>(byte-sequence-init BYTE-SEQUENCE) => BYTE-SEQUENCE</procedure> Returns a byte-sequence that contains all elements except the last element of the given byte-sequence. The argument byte-sequence must be non-empty, or an exception will be thrown. <procedure>(byte-sequence-uncons BYTE-SEQUENCE) => X BYTE-SEQUENCE</procedure> Returns two values, the first element of the given byte-sequence and a byte-sequence containing the remaining elements. Returns {{#f}} if the byte-sequence is empty. <procedure>(byte-sequence-unsnoc BYTE-SEQUENCE) => BYTE-SEQUENCE X</procedure> Returns two values, a byte-sequence containing all elements except the last, and the last element of the given byte-sequence. Returns {{#f}} if the byte-sequence is empty. <procedure>(byte-sequence-ref BYTE-SEQUENCE I) => BYTE</procedure> Returns the i-th element of the given byte-sequence as a signed byte. <procedure>(byte-sequence-uref BYTE-SEQUENCE I) => BYTE</procedure> Returns the i-th element of the given byte-sequence as an unsigned byte. <procedure>(byte-sequence-index-maybe BYTE-SEQUENCE I) => BYTE</procedure> Returns the i-th element of the given byte-sequence as an unsigned byte, or {{#f}} if {{I}} is out of range. ==== Transformers <procedure>(byte-sequence-set! BYTE-SEQUENCE I V) => VOID</procedure> Sets the i-th element of the given byte-sequence to the signed byte {{V}}. <procedure>(byte-sequence-uset! BYTE-SEQUENCE I V) => VOID</procedure> Sets the i-th element of the given byte-sequence to the unsigned byte {{V}}. <procedure>(byte-sequence-append BYTE-SEQUENCE BYTE-SEQUENCE) => BYTE-SEQUENCE</procedure> Appends two byte-sequences together. <procedure>(byte-sequence-reverse BYTE-SEQUENCE) => BYTE-SEQUENCE</procedure> Returns a byte-sequence that contains the elements of the given byte-sequence in reverse order. <procedure>(byte-sequence-intersperse BYTE-SEQUENCE BYTE) => BYTE-SEQUENCE</procedure> Returns a byte-sequence with the given byte placed between the elements of the given byte-sequence. <procedure>(byte-sequence-map F BYTE-SEQUENCE) => BYTE-SEQUENCE</procedure> Returns a byte-sequence obtained by applying {{F}} to each element of the given byte-sequence. <procedure>(byte-sequence->bytevector BYTE-SEQUENCE) => BYTEVECTOR</procedure> Returns the underlying Scheme bytevector object. <procedure>(byte-sequence->list BYTE-SEQUENCE [F]) => LIST</procedure> Returns a list containing the elements of the given byte-sequence. If procedure {{F}} is provided as a second argument, it is applied to every element of the returned list. <procedure>(byte-sequence->string BYTE-SEQUENCE) => STRING</procedure> Returns a string containing the elements of the given byte-sequence. ==== Comparison <procedure>(byte-sequence=? BYTE-SEQUENCE BYTE-SEQUENCE) => BOOL</procedure> Returns {{#t}} if the two byte-sequences contain the same sequence of bytes, {{#f}} otherwise. <procedure>(byte-sequence-compare BYTE-SEQUENCE BYTE-SEQUENCE) => INTEGER</procedure> Lexicographic comparison of two byte-sequences. Returns {{-1}}, {{0}}, or {{1}} as the first argument is less than, equal to, or greater than the second. ==== Searching <procedure>(byte-sequence-elem-index BYTE BYTE-SEQUENCE) => INTEGER</procedure> Returns the index of the first occurrence of {{BYTE}} in the given byte-sequence, or {{#f}} if the byte-sequence does not contain it. <procedure>(byte-sequence-elem-index-end BYTE BYTE-SEQUENCE) => INTEGER</procedure> Returns the index of the last occurrence of {{BYTE}} in the given byte-sequence, or {{#f}} if the byte-sequence does not contain it. <procedure>(byte-sequence-elem-indices BYTE BYTE-SEQUENCE) => LIST</procedure> Returns a list of the indices of all occurrences of {{BYTE}} in the given byte-sequence, in increasing order. <procedure>(byte-sequence-find-index F BYTE-SEQUENCE) => INTEGER</procedure> Returns the index of the first byte in the given byte-sequence that satisfies the predicate {{F}}, or {{#f}} if no byte does. <procedure>(byte-sequence-find-index-end F BYTE-SEQUENCE) => INTEGER</procedure> Returns the index of the last byte in the given byte-sequence that satisfies the predicate {{F}}, or {{#f}} if no byte does. <procedure>(byte-sequence-find-indices F BYTE-SEQUENCE) => LIST</procedure> Returns a list of the indices of all bytes in the given byte-sequence that satisfy the predicate {{F}}, in increasing order. <procedure>(byte-sequence-count BYTE BYTE-SEQUENCE) => INTEGER</procedure> Returns the number of occurrences of {{BYTE}} in the given byte-sequence. ==== Subsequences <procedure>(byte-sequence-take BYTE-SEQUENCE N) => BYTE-SEQUENCE</procedure> Returns the prefix of the given byte-sequence of length {{N}}, or the entire byte-sequence if {{N}} is greater than its length. <procedure>(byte-sequence-drop BYTE-SEQUENCE N) => BYTE-SEQUENCE</procedure> Returns the suffix of the given byte-sequence after the first {{N}} elements. <procedure>(byte-sequence-span BYTE-SEQUENCE START END) => BYTE-SEQUENCE</procedure> Returns the subsequence of the given byte-sequence from position {{START}} to position {{END}}. <procedure>(byte-sequence-take-end BYTE-SEQUENCE N) => BYTE-SEQUENCE</procedure> Returns the suffix of the given byte-sequence of length {{N}}, or the entire byte-sequence if {{N}} is greater than its length. <procedure>(byte-sequence-drop-end BYTE-SEQUENCE N) => BYTE-SEQUENCE</procedure> Returns the given byte-sequence with its last {{N}} elements removed, or the empty byte-sequence if {{N}} is greater than its length. <procedure>(byte-sequence-split-at BYTE-SEQUENCE N) => BYTE-SEQUENCE BYTE-SEQUENCE</procedure> Returns two values, the prefix of the given byte-sequence of length {{N}} and the remainder, as byte-sequences. If {{N}} is greater than the length of the byte-sequence, the prefix is the entire byte-sequence and the remainder is empty. <procedure>(byte-sequence-take-while F BYTE-SEQUENCE) => BYTE-SEQUENCE</procedure> Returns the longest prefix of the given byte-sequence whose bytes all satisfy the predicate {{F}}. <procedure>(byte-sequence-drop-while F BYTE-SEQUENCE) => BYTE-SEQUENCE</procedure> Returns the given byte-sequence with the longest prefix whose bytes all satisfy the predicate {{F}} removed. <procedure>(byte-sequence-take-while-end F BYTE-SEQUENCE) => BYTE-SEQUENCE</procedure> Returns the longest suffix of the given byte-sequence whose bytes all satisfy the predicate {{F}}. <procedure>(byte-sequence-drop-while-end F BYTE-SEQUENCE) => BYTE-SEQUENCE</procedure> Returns the given byte-sequence with its longest suffix whose bytes all satisfy the predicate {{F}} removed. <procedure>(byte-sequence-span-while F BYTE-SEQUENCE) => BYTE-SEQUENCE BYTE-SEQUENCE</procedure> Returns two values, the longest prefix of the given byte-sequence whose bytes all satisfy the predicate {{F}}, and the remainder. <procedure>(byte-sequence-break-while F BYTE-SEQUENCE) => BYTE-SEQUENCE BYTE-SEQUENCE</procedure> Returns two values, the longest prefix of the given byte-sequence whose bytes all fail the predicate {{F}}, and the remainder. <procedure>(byte-sequence-span-while-end F BYTE-SEQUENCE) => BYTE-SEQUENCE BYTE-SEQUENCE</procedure> Returns two values, the longest suffix of the given byte-sequence whose bytes all satisfy the predicate {{F}}, and the rest. <procedure>(byte-sequence-break-while-end F BYTE-SEQUENCE) => BYTE-SEQUENCE BYTE-SEQUENCE</procedure> Returns two values, the longest suffix of the given byte-sequence whose bytes all fail the predicate {{F}}, and the rest. <procedure>(byte-sequence-strip-prefix PREFIX BYTE-SEQUENCE) => BYTE-SEQUENCE</procedure> Returns the remainder of {{BYTE-SEQUENCE}} without its first {{N}} bytes, if the first {{N}} bytes match {{PREFIX}}, {{#f}} otherwise. <procedure>(byte-sequence-strip-suffix SUFFIX BYTE-SEQUENCE) => BYTE-SEQUENCE</procedure> Returns the prefix of {{BYTE-SEQUENCE}} without its last {{N}} bytes, if the last {{N}} bytes match {{SUFFIX}}, {{#f}} otherwise. ==== Fold <procedure>(byte-sequence-fold-left F INIT BYTE-SEQUENCE) => VALUE</procedure><br> <procedure>(byte-sequence-fold-right F INIT BYTE-SEQUENCE) => VALUE</procedure><br> Given a procedure of two arguments, a starting value, and a byte-sequence, reduces the byte-sequence using the supplied procedure, from left to right, or right to left, respectively. ==== Find <procedure>(byte-sequence-find NEEDLE HAYSTACK) => LIST</procedure> Finds all non-overlapping instances of the byte-sequence {{NEEDLE}} in the byte-sequence {{HAYSTACK}}. The first element of the returned list is the prefix of {{HAYSTACK}} prior to any matches of {{NEEDLE}}. The second is a list of lists. The first element of each pair in the list is a span from the beginning of a match to the beginning of the next match, while the second is a span from the beginning of the match to the end of the input. ==== I/O <procedure>(file->byte-sequence FILENAME [MODE]) => BYTE-SEQUENCE</procedure> Returns a byte-sequence with the contents of the given file. {{MODE}} is an optional argument that can be one of {{#:text}} or {{#:binary}} to specify text or binary mode on Windows. <procedure>(byte-sequence->file FILENAME BYTE-SEQUENCE [MODE]) => UNDEFINED</procedure> Writes the given byte-sequence to the file named by {{FILENAME}}. {{MODE}} is an optional argument that is passed to {{call-with-output-file}}, so {{#:append}} can be used to append to an existing file. <procedure>(byte-sequence-read PORT N) => BYTE-SEQUENCE</procedure> Reads a byte-sequence of length {{N}} from the given port. Currently, the port must support the {{port->fileno}} procedure, which means that string ports are not supported (in that particular case, procedure {{string->byte-sequence}} can be used for converting strings to byte sequences). <procedure>(byte-sequence-write PORT BYTE-SEQUENCE) => UNDEFINED</procedure> Writes the given byte-sequence to the given port. Currently, the port must support the {{port->fileno}} procedure, which means that string ports are not supported (in that particular case, procedure {{string->byte-sequence}} can be used for converting strings to byte sequences). ==== SRFI-4 transformers <procedure>(u8vector->byte-sequence U8VECTOR) => BYTE-SEQUENCE</procedure><br> <procedure>(s8vector->byte-sequence S8VECTOR) => BYTE-SEQUENCE</procedure><br> <procedure>(u16vector->byte-sequence U16VECTOR) => BYTE-SEQUENCE</procedure><br> <procedure>(s16vector->byte-sequence S16VECTOR) => BYTE-SEQUENCE</procedure><br> <procedure>(u32vector->byte-sequence U32VECTOR) => BYTE-SEQUENCE</procedure><br> <procedure>(s32vector->byte-sequence S32VECTOR) => BYTE-SEQUENCE</procedure><br> <procedure>(f32vector->byte-sequence F32VECTOR) => BYTE-SEQUENCE</procedure><br> <procedure>(f64vector->byte-sequence F64VECTOR) => BYTE-SEQUENCE</procedure><br> <procedure>(byte-sequence->u8vector BYTE-SEQUENCE) => U8VECTOR</procedure><br> <procedure>(byte-sequence->s8vector BYTE-SEQUENCE) => S8VECTOR</procedure><br> <procedure>(byte-sequence->u16vector BYTE-SEQUENCE) => U16VECTOR</procedure><br> <procedure>(byte-sequence->s16vector BYTE-SEQUENCE) => S16VECTOR</procedure><br> <procedure>(byte-sequence->u32vector BYTE-SEQUENCE) => U32VECTOR</procedure><br> <procedure>(byte-sequence->s32vector BYTE-SEQUENCE) => S32VECTOR</procedure><br> <procedure>(byte-sequence->f32vector BYTE-SEQUENCE) => F32VECTOR</procedure><br> <procedure>(byte-sequence->f64vector BYTE-SEQUENCE) => F64VECTOR</procedure><br> Note: in CHICKEN 6, u8vectors are represented directly as bytevectors, so {{byte-sequence->u8vector}} and {{byte-sequence->bytevector}} return the same kind of object. === Repository [[https://github.com/iraikov/chicken-byte-blob|https://github.com/iraikov/chicken-byte-blob]] === Version History * 3.0 Renamed to byte-sequence. The procedures {{blob->byte-blob}} and {{byte-blob->blob}} are now {{bytevector->byte-sequence}} and {{byte-sequence->bytevector}} * 2.5 Ported to CHICKEN 6; added several procedures inspired by the Haskell bytestring library * 2.3 Previous byte-blob release * 1.19 Ported to CHICKEN 5 * 1.18 Added optional mode argument to file->byte-blob (thanks to dthedens) * 1.17 Added documentation for byte-blob->blob procedure (reported by retroj) * 1.16 Remove files created by unit tests (thanks to mario) * 1.15 Fixes for issues #1037 and #1038 (thanks to dthedens) * 1.14 Bug fix in byte-blob-find * 1.13 Added byte-blob-uref and byte-blob-uset! (thanks to Panos Stergiotis) * 1.12 Fixed a bug in byte-blob-drop; added byte-blob-set! (thanks to Panos Stergiotis) * 1.11 Updated test script to return proper exit code * 1.9 Bug fix in byte-blob-find * 1.8 Changed (import posix) to (require-extension posix) * 1.7 Bug fix in byte-blob->string * 1.6 Added optional second argument to byte-blob->list * 1.5 Bug fixes in {{byte-blob-read}} and {{byte-blob-write}} * 1.4 Added procedure {{blob->byte-blob}} * 1.3 Fix in invocation of chicken_Panic * 1.2 Added procedure {{byte-blob-ref}} * 1.0 Initial release === License Based on ideas from the Haskell [[https://hackage.haskell.org/package/bytestring/|bytestring]] library. The code for {{byte-sequence-find}} is based on code from the Haskell Text library by Tom Harper and Bryan O'Sullivan. Copyright 2009-2026 Ivan Raikov, Dan Thedens. This program is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. A full copy of the GPL license can be found at <http://www.gnu.org/licenses/>.Description of your changes:

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